Vehicles, such as pickup trucks, have a rear window, or backlite, that is assembled into an opening in the body panel immediately behind the operator's seat. These backlites are provided to the truck manufacturer, or the after-market, as window frame assemblies. The current window frame assemblies that are commercially available generally have a welded metal frame, usually aluminum, which is sized to fit in a body panel opening. The frame has a generally bow-shaped outline, when viewed in elevation, with the upper corners being curved to fit the body panel opening. The upper portion of the frame provides the bow shape, and the lower rail portion, which is generally linear, is welded to the ends of the upper portion. Specifically, the upper and lower portions have beveled ends which are welded together to form the metal frame.
A continuous channel, the opening of which faces inwardly, is provided in the frame to support the upper and lower edges of the sliding window pane, or panes. A second inwardly opening channel supports a pair of fixed window panes. The side edges of the fixed window panes, adjacent the sliding window pane(s), are supported by vertical struts which are secured between the upper and lower portions of the frame. The remaining sides of the fixed window panes are each secured to, and are sealed in, the frame. A separate seal, having a lip adapted to engage the sliding window pane(s), is provided along the upper and lower edges of the sliding window pane(s) to prevent leakage of moisture to the interior of the vehicle when they are closed.
On occasion, the outer surface of the window frame assemblies have been provide with various decorative treatments. As a general rule, however, the outer surface is simply an exposed aluminum surface, or, as is frequently encountered, the frame may be coated with an elastomeric material which also covers the exposed outer surface of the frame. When the metallic window frame is exposed, a closure member is disposed to provide a sealing interface with the sliding windows, which, when closed, are generally disposed centrally of the frame, and, when open, are positioned behind the fixed windows. These assemblies are often secured to the vehicle body panel by a bead of urethane adhesive material. It must be kept in mind, however, that the frame assembly must be positionably inserted in the opening of the body panel with extreme care in order to ensure that the paint on the body panel is not scratched by the exposed metal of the frame during the procedure by which the frame assembly is mounted on the body panel of the vehicle.
Those window frame assemblies having an elastomeric covering, or having the periphery encapsulated within a gasket, are of two types--one of which does not have any exposed metal edges, thereby minimizing the possibility of defacing, or scratching, the painted surface of the vehicle during installation of the frame assembly. The assemblies that are so covered, or encapsulated, do, however, require a considerable amount of assembly time. For example, the gasket must be stretched over the frame. Gaskets for this purpose are normally provided with a groove which cooperates with a metal edge on the body panel opening. A separate sealing member is usually provided and is secured in the same channel within which the fixed windows are supported.
In order to mount this type window, the frame assembly is positioned in the appropriate opening, and the groove, presented from the gasket is stretched over the edge of the body panel to secure the assembly in the opening. The assembler must take care not to cut the gasket on the exposed metal edge inasmuch as a cut could not only result in an air, or liquid, leak but also constitute a noise source during vehicle operation. If the gasket is cut, a urethane adhesive or sealant must be applied. This is time consuming and increases the cost of assembly. The assembler must also be aware of the sharpness of the metal edge so that injuries, due to lacerations, do not occur.
Those frame assemblies employing an elastomeric covering generally include an integrally formed seal that is bonded only at the outer facing surface of the metal frame. As such, this arrangement requires the exercise of considerable care during installation. This type of window frame assembly is normally bonded to the body panel using a urethane adhesive.
Yet other frame assemblies have been provided that use a coating which is sprayed onto, or otherwise bonded to, the surface of the metal frame. As might be expected, considerable care must be taken to prevent the thin coating from being scratched or cut, both during storage and during the procedure by which the frame assembly is mounted in the panel opening of a vehicle. This type frame assembly requires that the manufacturer invest in spraying, or bonding, equipment which is expensive to purchase, install and maintain.